Shoeln,

Just on the consistency aspect you say your looking at the beaten margin at their last 4 starts.
Horses that were placed close up at their last 4 starts will more than likely be over bet,if you could re jig that to look at the best 3 finishes of the last 4 starts you might get a bit more value in your selections and you would not be penalising a horse for having an off day,as they do sometimes.